NCP1450A PWM Step−up DC−DC Controller The NCP1450A series are PWM step−up DC−DC switching controller that are specially designed for powering portable equipment from one or two cells battery packs. The NCP1450A series have a driver pin, EXT pin, for connecting to an external transistor. Large output currents can be obtained by connecting a low ON−resistance external power transistor to the EXT pin. The device will automatically skip switching cycles under light load condition to maintain high efficiency at light loads. With only six external components, this series allows a simple means to implement highly efficient converter for large output current applications. Each device consists of an on−chip Pulse Width Modulation (PWM) oscillator, PWM controller, phase−compensated error amplifier, soft−start, voltage reference, and driver for driving external power transistor. Additionally, a chip enable feature is provided to power down the converter for extended battery life. The NCP1450A device series are available in the TSOP−5 package with five standard regulated output voltages. Additional voltages that range from 1.8 V to 5.0 V in 100 mV steps can be manufactured. • High Efficiency 86% at IO = 200 mA, VIN = 2.0 V, VOUT = 3.0 V • • • • • • • • • 88% at IO = 400 mA, VIN = 3.0 V, VOUT = 5.0 V Low Startup Voltage of 0.9 V typical at IO = 1.0 mA Operation Down to 0.6 V Five Standard Voltages: 1.9 V, 2.7 V, 3.0 V, 3.3 V, 5.0 V with High Accuracy ± 2.5% Low Conversion Ripple High Output Current up to 1000 mA (3.0 V version at VIN = 2.0 V, L = 10 H, COUT = 220 F) Fixed Frequency Pulse Width Modulation (PWM) at 180 kHz Chip Enable Pin with On−chip 150 nA Pullup Current Source Low Profile and Micro Miniature TSOP−5 Package Pb−Free Packages are Available 5 1 TSOP−5 SN SUFFIX CASE 483 MARKING DIAGRAM AND PIN CONNECTIONS CE 1 OUT 2 NC 3 5 EXT 4 GND xxxAYWG G Features http://onsemi.com (Top View) xxx =Specific Device Marking A = Assembly Location Y = Year W = Work Week G = Pb−Free Package (Note: Microdot may be in either location) ORDERING INFORMATION See detailed ordering and shipping information in the ordering information section on page 3 of this data sheet. Typical Applications • • • • • Personal Digital Assistant (PDA) Electronic Games Portable Audio (MP3) Digital Still Cameras Handheld Instruments © Semiconductor Components Industries, LLC, 2005 December, 2005 − Rev. 7 1 Publication Order Number: NCP1450A/D NCP1450A VOUT CE 1 OUT 2 NC 3 NCP1450A VIN EXT 5 GND 4 Figure 1. Typical Step−up Converter Application OUT 2 + − NC 3 Error Amplifier PWM Controller Phase Compensation Voltage Reference Driver EXT 5 180 kHz Oscillator Soft−Start GND 4 1 CE Figure 2. Representative Block Diagram PIN FUNCTION DESCRIPTION ÁÁÁÁÁ ÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ Pin # Symbol Pin Description 1 CE 2 OUT 3 NC 4 GND Ground pin. 5 EXT External transistor drive pin. Chip Enable Pin (1) The chip is enabled if a voltage equal to or greater than 0.9 V is applied. (2) The chip is disabled if a voltage less than 0.3 V is applied. (3) The chip is enabled if this pin is left floating. Output voltage monitor pin and also the power supply pin for the device. No internal connection to this pin. http://onsemi.com 2 NCP1450A ORDERING INFORMATION (Note 1) Device Output Voltage Switching Frequency Marking NCP1450ASN19T1 NCP1450ASN19T1G TSOP−5 1.9 V DAY TSOP−5 (Pb−Free) NCP1450ASN27T1G NCP1450ASN27T1 TSOP−5 2.7 V DAZ TSOP−5 (Pb−Free) NCP1450ASN30T1 NCP1450ASN30T1G TSOP−5 3.0 V 180 KHz DBA TSOP−5 3.3 V DBC TSOP−5 (Pb−Free) NCP1450ASN50T1 NCP1450ASN50T1G 3000 Units on 7 Inch Reel TSOP−5 (Pb−Free) NCP1450ASN33T1 NCP1450ASN33T1G Shipping† Package TSOP−5 5.0 V DBD TSOP−5 (Pb−Free) †For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging Specifications Brochure, BRD8011/D. 1. The ordering information lists five standard output voltage device options. Additional devices with output voltage ranging from 1.8 V to 5.0 V in 100 mV increments can be manufactured. Contact your ON Semiconductor representative for availability. MAXIMUM RATINGS ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁ ÁÁÁÁÁÁÁ ÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁ ÁÁÁÁÁÁÁ ÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁ ÁÁÁÁÁÁÁ ÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁ ÁÁÁÁÁÁÁ ÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ Rating Symbol Value Unit Power Supply Voltage (Pin 2) VOUT 6.0 V Input/Output Pins EXT (Pin 5) EXT Sink/Source Current VEXT IEXT −0.3 to 6.0 −150 to 150 V mA CE (Pin 1) Input Voltage Range Input Current Range VCE ICE −0.3 to 6.0 −150 to 150 V mA Power Dissipation and Thermal Characteristics Maximum Power Dissipation @ TA = 25°C Thermal Resistance Junction−to−Air PD RJA 500 250 mW °C/W Operating Ambient Temperature Range TA −40 to +85 °C Operating Junction Temperature Range TJ −40 to +150 °C Storage Temperature Range Tstg −55 to +150 °C Maximum ratings are those values beyond which device damage can occur. Maximum ratings applied to the device are individual stress limit values (not normal operating conditions) and are not valid simultaneously. If these limits are exceeded, device functional operation is not implied, damage may occur and reliability may be affected. 2. This device series contains ESD protection and exceeds the following tests: Human Body Model (HBM) $2.0 kV per JEDEC standard: JESD22−A114. Machine Model (MM) $200 V per JEDEC standard: JESD22−A115. 3. Latchup Current Maximum Rating: $150 mA per JEDEC standard: JESD78. 4. Moisture Sensitivity Level (MSL): 1 per IPC/JEDEC standard: J−STD−020A. http://onsemi.com 3 NCP1450A ELECTRICAL CHARACTERISTICS (For all values TA = 25°C, unless otherwise noted.) Characteristic Symbol Min Typ Max fOSC f Unit 144 180 216 kHz − 0.11 − %/°C DMAX 70 80 90 % OSCILLATOR Frequency (VOUT = VSET 0.96, Note 5) Frequency Temperature Coefficient (TA = −40°C to 85°C) Maximum PWM Duty Cycle (VOUT = VSET 0.96) Minimum Startup Voltage (IO = 0 mA) Minimum Startup Voltage Temperature Coefficient (TA = −40°C to 85°C) Minimum Operation Hold Voltage (IO = 0 mA) Soft−Start Time (VOUT = VSET, Note 6) Vstart − 0.8 0.9 V Vstart − −1.6 − mV/°C Vhold − 0.6 0.7 V tSS − 100 250 ms VCE(high) VCE(low) 0.9 − − − − 0.3 ICE(high) ICE(low) −0.5 0 0 0.15 0.5 0.5 CE (PIN 1) CE Input Voltage (VOUT = VSET High State, Device Enabled Low State, Device Disabled 0.96) V A CE Input Current (Note 6) High State, Device Enabled (VOUT = VCE = 5.0 V) Low State, Device Disabled (VOUT = 5.0 V, VCE = 0 V) EXT (PIN 5) EXT “H” Output Current (VEXT = VOUT −0.4 V) Device Suffix: 19T1 27T1 30T1 33T1 50T1 IEXTH EXT “L” Output Current(VEXT = 0.4 V) Device Suffix: 19T1 27T1 30T1 33T1 50T1 IEXTL mA − − − − − −25.0 −35.0 −37.7 −40.0 −53.7 −20.0 −30.0 −30.0 −30.0 −35.0 mA 20.0 30.0 30.0 30.0 35.0 38.3 48.0 50.8 52.0 58.2 − − − − − TOTAL DEVICE VOUT Output Voltage Device Suffix: 19T1 27T1 30T1 33T1 50T1 VOUT Output Voltage Temperature Coefficient (TA = −40 to +85°C) Operating Current (VOUT = VCE = VSET Device Suffix: 19T1 27T1 30T1 33T1 50T1 0.96, Note 5) V 1.853 2.633 2.925 3.218 4.875 1.9 2.7 3.0 3.3 5.0 1.948 2.768 3.075 3.383 5.125 − 150 − ppm/°C A IDD − − − − − 55 93 98 103 136 90 140 150 160 220 Standby Current (VOUT = VCE = VSET +0.5 V) ISTB − 15 20 A Off−State Current (VOUT = 5.0 V, VCE = 0 V, TA = −40 to +85°C, Note 7) IOFF − 0.6 1.5 A 5. VSET means setting of output voltage. 6. This parameter is guaranteed by design. 7. CE pin is integrated with an internal 150 nA pullup current source. http://onsemi.com 4 NCP1450A 3.2 VOUT, OUTPUT VOLTAGE (V) VOUT, OUTPUT VOLTAGE (V) 2.1 2.0 1.9 VIN = 0.9 V VIN = 1.2 V VIN = 1.5 V 1.8 NCP1450ASN19T1 L = 10 H Q = NTGS3446T1 COUT = 220 F TA = 25°C 1.7 0 200 400 800 600 3.0 VIN = 0.9 V VIN = 1.2 V 2.9 VIN = 2.0 V VIN = 1.5 V NCP1450ASN30T1 L = 10 H Q = NTGS3446T1 COUT = 220 F TA = 25°C 2.8 1000 0 200 400 600 800 1000 IO, OUTPUT CURRENT (mA) IO, OUTPUT CURRENT (mA) Figure 3. NCP1450ASN19T1 Output Voltage vs. Output Current Figure 4. NCP1450ASN30T1 Output Voltage vs. Output Current 100 5.2 VIN = 1.5 V VIN = 4.5 V 5.1 VIN = 1.2 V VIN = 2.0 V 80 VIN = 4.0 V EFFICIENCY (%) VOUT, OUTPUT VOLTAGE (V) VIN = 2.5 V 2.7 1.6 5.0 VIN = 2.5 V VIN = 1.5 V VIN = 3.0 V 4.9 NCP1450ASN50T1 L = 10 H Q = NTGS3446T1 COUT = 220 F TA = 25°C VIN = 0.9 V 4.8 0 200 400 600 800 VIN = 0.9 V 40 NCP1450ASN19T1 L = 10 H Q = NTGS3446T1 COUT = 220 F TA = 25°C 0.1 1 10 100 IO, OUTPUT CURRENT (mA) IO, OUTPUT CURRENT (mA) Figure 5. NCP1450ASN50T1 Output Voltage vs. Output Current Figure 6. NCP1450ASN19T1 Efficiency vs. Output Current 100 VIN = 2.5 V VIN = 2.0 V EFFICIENCY (%) VIN = 1.5 V 60 40 20 VIN = 1.2 V VIN = 0.9 V 0 0.01 60 0 0.01 1000 100 80 VIN = 1.2 V 20 4.7 EFFICIENCY (%) 3.1 0.1 1 NCP1450ASN30T1 L = 10 H Q = NTGS3446T1 COUT = 220 F TA = 25°C 10 100 VIN = 4.0 V VIN = 3.0 V 80 VIN = 2.5 V VIN = 2.0 V VIN = 4.5 V VIN = 1.2 V 60 VIN = 0.9 V VIN = 1.5 V 40 NCP1450ASN50T1 L = 10 H Q = NTGS3446T1 COUT = 220 F TA = 25°C 20 0 0.01 1000 0.1 1 10 100 IO, OUTPUT CURRENT (mA) IO, OUTPUT CURRENT (mA) Figure 7. NCP1450ASN30T1 Efficiency vs. Output Current Figure 8. NCP1450ASN50T1 Efficiency vs. Output Current http://onsemi.com 5 1000 1000 NCP1450A 3.2 VOUT, OUTPUT VOLTAGE (V) VOUT, OUTPUT VOLTAGE (V) 2.1 2.0 1.9 1.8 1.7 1.6 −50 NCP1450ASN19T1 L = 22 H IO = 0 mA VIN = 1.2 V −25 0 25 50 75 0 25 50 75 100 100 IDD, OPERATING CURRENT (A) VOUT, OUTPUT VOLTAGE (V) −25 Figure 10. NCP1450ASN30T1 Output Voltage vs. Temperature NCP1450ASN50T1 L = 22 H IO = 0 mA VIN = 1.2 V −25 0 25 50 75 80 60 40 20 0 −50 100 NCP1450ASN19T1 VOUT = 1.9 V x 0.96 Open−Loop Test −25 0 25 50 75 TEMPERATURE (°C) TEMPERATURE (°C) Figure 11. NCP1450ASN50T1 Output Voltage vs. Temperature Figure 12. NCP1450ASN19T1 Operating Current vs. Temperature 100 200 IDD, OPERATING CURRENT (A) 140 IDD, OPERATING CURRENT (A) NCP1450ASN30T1 L = 22 H IO = 0 mA VIN = 1.2 V Figure 9. NCP1450ASN19T1 Output Voltage vs. Temperature 4.9 120 100 80 40 −50 2.8 TEMPERATURE (°C) 5.0 60 2.9 TEMPERATURE (°C) 5.1 4.7 −50 3.0 2.7 −50 100 5.2 4.8 3.1 NCP1450ASN30T1 VOUT = 3.0 V x 0.96 Open−Loop Test −25 0 25 50 75 180 160 140 120 100 −50 100 NCP1450ASN50T1 VOUT = 5.0 V x 0.96 Open−Loop Test −25 0 25 50 75 TEMPERATURE (°C) TEMPERATURE (°C) Figure 13. NCP1450ASN30T1 Operating Current vs. Temperature Figure 14. NCP1450ASN50T1 Operating Current vs. Temperature http://onsemi.com 6 100 NCP1450A 25 ISTD, STANDBY CURRENT (A) ISTD, STANDBY CURRENT (A) 25 20 15 10 NCP1450ASN19T1 VOUT = 1.9 V + 0.5 V Open−Loop Test 5 0 −50 −25 0 25 50 75 10 NCP1450ASN30T1 VOUT = 3.0 V + 0.5 V Open−Loop Test 5 −25 0 25 50 75 100 TEMPERATURE (°C) TEMPERATURE (°C) Figure 15. NCP1450ASN19T1 Standby Current vs. Temperature Figure 16. NCP1450ASN30T1 Standby Current vs. Temperature 1.0 IOFF, OFF−STATE CURRENT (A) ISTD, STANDBY CURRENT (A) 15 0 −50 100 25 20 15 10 NCP1450ASN50T1 VOUT = 5.0 V + 0.5 V Open−Loop Test 5 0 −50 −25 0 25 50 75 NCP1450ASN19T1 VOUT = 5.0 V VCE = 0 V Open−Loop Test 0.8 0.6 0.4 0.2 0.0 −50 100 −25 0 25 50 75 100 TEMPERATURE (°C) TEMPERATURE (°C) Figure 17. NCP1450ASN50T1 Standby Current vs. Temperature Figure 18. NCP1450ASN19T1 Off−State Current vs. Temperature 1.2 1.0 NCP1450ASN30T1 VOUT = 5.0 V VCE = 0 V Open−Loop Test 0.8 IOFF, OFF−STATE CURRENT (A) IOFF, OFF−STATE CURRENT (A) 20 0.6 0.4 0.2 0.0 −50 −25 0 25 50 75 NCP1450ASN50T1 VOUT = 5.0 V VCE = 0 V Open−Loop Test 1.0 0.8 0.6 0.4 0.2 −50 100 −25 0 25 50 75 100 TEMPERATURE (°C) TEMPERATURE (°C) Figure 19. NCP1450ASN30T1 Off−State Current vs. Temperature Figure 20. NCP1450ASN50T1 Off−State Current vs. Temperature http://onsemi.com 7 fOSC, OSCILLATOR FREQUENCY (kHz) 300 250 200 150 100 NCP1450ASN19T1 VOUT = 1.9 V x 0.96 Open−Loop Test 50 0 −50 −25 0 25 50 75 100 250 200 150 100 NCP1450ASN30T1 VOUT = 3.0 V x 0.96 Open−Loop Test 50 0 −50 −25 0 25 50 75 TEMPERATURE (°C) Figure 21. NCP1450ASN19T1 Oscillator Frequency vs. Temperature Figure 22. NCP1450ASN30T1 Oscillator Frequency vs. Temperature 300 100 100 250 200 150 100 NCP1450ASN50T1 VOUT = 5.0 V x 0.96 Open−Loop Test 50 0 −50 −25 0 25 50 75 90 80 70 60 NCP1450ASN19T1 VOUT = 1.9 V x 0.96 Open−Loop Test 50 40 −50 100 −25 0 25 50 75 TEMPERATURE (°C) TEMPERATURE (°C) Figure 23. NCP1450ASN50T1 Oscillator Frequency vs. Temperature Figure 24. NCP1450ASN19T1 Maximum Duty Cycle vs. Temperature 100 100 DMAX, MAXIMUM DUTY CYCLE (%) 100 DMAX, MAXIMUM DUTY CYCLE (%) 300 TEMPERATURE (°C) DMAX, MAXIMUM DUTY CYCLE (%) fOSC, OSCILLATOR FREQUENCY (kHz) fOSC, OSCILLATOR FREQUENCY (kHz) NCP1450A 90 80 70 60 NCP1450ASN30T1 VOUT = 3.0 V x 0.96 Open−Loop Test 50 40 −50 −25 0 25 50 75 90 80 70 60 NCP1450ASN50T1 VOUT = 5.0 V x 0.96 Open−Loop Test 50 40 −50 100 −25 0 25 50 75 TEMPERATURE (°C) TEMPERATURE (°C) Figure 25. NCP1450ASN30T1 Maximum Duty Cycle vs. Temperature Figure 26. NCP1450ASN50T1 Maximum Duty Cycle vs. Temperature http://onsemi.com 8 100 IEXTH, EXT “H” OUTPUT CURRENT (mA) 0 −10 −20 −30 NCP1450ASN19T1 VOUT = 1.9 V x 0.96 VEXT = VOUT − 0.4 V Open−Loop Test −40 −50 −50 −25 0 25 50 75 100 −20 −30 −40 −50 NCP1450ASN30T1 VOUT = 3.0 V x 0.96 VEXT = VOUT − 0.4 V Open−Loop Test −60 −70 −50 −25 0 25 50 75 TEMPERATURE (°C) TEMPERATURE (°C) Figure 27. NCP1450ASN19T1 EXT “H” Output Current vs. Temperature Figure 28. NCP1450ASN30T1 EXT “H” Output Current vs. Temperature IEXTL, EXT “L” OUTPUT CURRENT (mA) −40 −50 −60 −70 NCP1450ASN50T1 VOUT = 5.0 V x 0.96 VEXT = VOUT − 0.4 V Open−Loop Test −80 −90 −50 −25 0 25 50 75 100 40 30 20 NCP1450ASN19T1 VOUT = 1.9 V x 0.96 VEXT = 0.4 V Open−Loop Test 10 0 −50 −25 0 25 50 75 TEMPERATURE (°C) Figure 29. NCP1450ASN50T1 EXT “H” Output Current vs. Temperature Figure 30. NCP1450ASN19T1 EXT “L” Output Current vs. Temperature 80 70 60 50 NCP1450ASN30T1 VOUT = 3.0 V x 0.96 VEXT = 0.4 V Open−Loop Test 40 30 −50 −25 0 25 50 75 100 100 90 80 70 60 NCP1450ASN50T1 VOUT = 5.0 V x 0.96 VEXT = 0.4 V Open−Loop Test 50 40 −50 −25 0 25 50 75 TEMPERATURE (°C) TEMPERATURE (°C) Figure 31. NCP1450ASN30T1 EXT “L” Output Current vs. Temperature Figure 32. NCP1450ASN50T1 EXT “L” Output Current vs. Temperature http://onsemi.com 9 100 50 TEMPERATURE (°C) IEXTL, EXT “L” OUTPUT CURRENT (mA) IEXTL, EXT “L” OUTPUT CURRENT (mA) IEXTH, EXT “H” OUTPUT CURRENT (mA) IEXTH, EXT “H” OUTPUT CURRENT (mA) NCP1450A 100 20 15 10 5 0 −50 NCP1450ASN19T1 VOUT = 1.9 V x 0.96 VEXT = VOUT − 0.4 V Open−Loop Test −25 0 25 50 75 100 10 5 0 −50 NCP1450ASN30T1 VOUT = 3.0 V x 0.96 VEXT = VOUT − 0.4 V Open−Loop Test −25 0 25 50 75 Figure 34. NCP1450ASN30T1 EXT “H” ON−Resistance vs. Temperature NCP1450ASN50T1 VOUT = 5.0 V x 0.96 VEXT = VOUT − 0.4 V Open−Loop Test 10 5 −25 0 25 50 75 20 NCP1450ASN19T1 VOUT = 1.9 V x 0.96 VEXT = 0.4 V Open−Loop Test 15 10 5 −25 0 25 50 75 TEMPERATURE (°C) TEMPERATURE (°C) Figure 35. NCP1450ASN50T1 EXT “H” ON−Resistance vs. Temperature Figure 36. NCP1450ASN19T1 EXT “L” ON−Resistance vs. Temperature NCP1450ASN30T1 VOUT = 3.0 V x 0.96 VEXT = 0.4 V Open−Loop Test 15 10 5 −25 0 25 50 75 100 100 25 20 NCP1450ASN50T1 VOUT = 5.0 V x 0.96 VEXT = 0.4 V Open−Loop Test 15 10 5 0 −50 −25 0 25 50 75 TEMPERATURE (°C) TEMPERATURE (°C) Figure 37. NCP1450ASN30T1 EXT “L” ON−Resistance vs. Temperature Figure 38. NCP1450ASN50T1 EXT “L” ON−Resistance vs. Temperature http://onsemi.com 10 100 25 0 −50 100 25 0 −50 15 Figure 33. NCP1450ASN19T1 EXT “H” ON−Resistance vs. Temperature 15 20 20 TEMPERATURE (°C) REXTL, EXT “L” ON−RESISTANCE () 20 25 TEMPERATURE (°C) 25 0 −50 REXTL, EXT “L” ON−RESISTANCE () REXTH, EXT “H” ON−RESISTANCE () 25 REXTL, EXT “L” ON−RESISTANCE () REXTH, EXT “H” ON−RESISTANCE () REXTH, EXT “H” ON−RESISTANCE () NCP1450A 100 Vstart/Vhold, STARTUP/HOLD VOLTAGE (V) 1.0 0.8 Vstart 0.6 0.4 NCP1450ASN19T1 L = 22 H COUT = 0.1 F IO = 0 mA Vhold 0.2 0.0 −50 −25 0 25 50 75 100 NCP1450ASN30T1 L = 22 H COUT = 0.1 F IO = 0 mA 0.6 0.4 Vhold 0.2 0.0 −50 −25 0 25 50 75 Figure 40. NCP1450ASN30T1 Startup/Hold Voltage vs. Temperature 100 200 Vstart 0.6 0.4 Vhold NCP1450ASN50T1 L = 22 H COUT = 0.1 F IO = 0 mA −25 0 NCP1450ASN19T1 L = 10 H Q = NTGS3446T1 COUT = 220 F TA = 25°C 180 160 140 120 100 VIN = 1.5 V VIN = 1.2 V VIN = 0.9 V 80 60 40 20 0 25 50 75 100 0 200 400 600 800 1000 TEMPERATURE (°C) IO, OUTPUT CURRENT (mA) Figure 41. NCP1450ASN50T1 Startup/Hold Voltage vs. Temperature Figure 42. NCP1450ASN19T1 Ripple Voltage vs. Output Current 200 NCP1450ASN30T1 L = 10 H Q = NTGS3446T1 COUT = 220 F TA = 25°C 180 160 140 120 100 VIN = 1.2 V VRIPPLE, RIPPLE VOLTAGE (mV) 200 VRIPPLE, RIPPLE VOLTAGE (mV) Vstart Figure 39. NCP1450ASN19T1 Startup/Hold Voltage vs. Temperature 0.8 0.0 −50 0.8 TEMPERATURE (°C) 1.0 0.2 1.0 TEMPERATURE (°C) VRIPPLE, RIPPLE VOLTAGE (mV) Vstart/Vhold, STARTUP/HOLD VOLTAGE (V) Vstart/Vhold, STARTUP/HOLD VOLTAGE (V) NCP1450A VIN = 1.5 V VIN = 0.9 V 80 VIN = 2.5 V 60 40 VIN = 2.0 V 20 0 180 VIN = 2.0 V 160 VIN = 2.5 V VIN = 0.9 V 140 120 VIN = 1.2 V 100 NCP1450ASN50T1 L = 10 H Q = NTGS3446T1 COUT = 220 F TA = 25°C VIN = 3.0 V VIN = 1.5 V 80 60 VIN = 4.5 V 40 VIN = 4.0 V 20 0 0 200 400 600 800 0 1000 200 400 600 800 1000 IO, OUTPUT CURRENT (mA) IO, OUTPUT CURRENT (mA) Figure 43. NCP1450ASN30T1 Ripple Voltage vs. Output Current Figure 44. NCP1450ASN50T1 Ripple Voltage vs. Output Current http://onsemi.com 11 Vstart 1.6 1.2 0.8 Vhold NCP1450ASN19T1 L = 10 H Q = NTGS3446T1 COUT = 220 F TA = 25°C 0.4 0.0 20 40 60 80 100 1.6 Vstart 1.2 0.8 Vhold 0.4 0.0 0 20 40 60 80 Figure 45. NCP1450ASN19T1 Startup/Hold Voltage vs. Output Current (Using MOSFET) Figure 46. NCP1450ASN19T1 Startup/Hold Voltage vs. Output Current (Using BJT) Vstart 1.6 NCP1450ASN30T1 L = 10 H Q = NTGS3446T1 COUT = 220 F TA = 25°C 1.2 0.8 Vhold 0.4 0.0 20 40 60 80 100 Vstart 1.6 1.2 Vhold 0.8 NCP1450ASN30T1 L = 10 H Q = MMJT9410 COUT = 220 F TA = 25°C 0.4 0.0 0 20 40 60 80 IO, OUTPUT CURRENT (mA) Figure 47. NCP1450ASN30T1 Startup/Hold Voltage vs. Output Current (Using MOSFET) Figure 48. NCP1450ASN30T1 Startup/Hold Voltage vs. Output Current (Using BJT) 1.6 Vstart 1.2 Vhold 0.8 NCP1450ASN50T1 L = 10 H Q = NTGS3446T1 COUT = 220 F TA = 25°C 0.4 0.0 20 40 60 80 100 100 2.0 Vstart 1.6 1.2 Vhold 0.8 NCP1450ASN50T1 L = 10 H Q = MMJT9410 COUT = 220 F TA = 25°C 0.4 0.0 0 20 40 60 80 IO, OUTPUT CURRENT (mA) IO, OUTPUT CURRENT (mA) Figure 49. NCP1450ASN50T1 Startup/Hold Voltage vs. Output Current (Using MOSFET) Figure 50. NCP1450ASN50T1 Startup/Hold Voltage vs. Output Current (Using BJT) http://onsemi.com 12 100 2.0 IO, OUTPUT CURRENT (mA) 2.0 0 NCP1450ASN19T1 L = 10 H Q = MMJT9410 COUT = 220 F TA = 25°C IO, OUTPUT CURRENT (mA) 2.0 0 2.0 IO, OUTPUT CURRENT (mA) Vstart/Vhold, STARTUP/HOLD VOLTAGE (V) 0 Vstart/Vhold, STARTUP/HOLD VOLTAGE (V) 2.0 Vstart/Vhold, STARTUP/HOLD VOLTAGE (V) Vstart/Vhold, STARTUP/HOLD VOLTAGE (V) Vstart/Vhold, STARTUP/HOLD VOLTAGE (V) Vstart/Vhold, STARTUP/HOLD VOLTAGE (V) NCP1450A 100 NCP1450A 2 s/div VOUT = 1.9 V, VIN = 1.2 V, IO = 20 mA, L = 10 H, COUT = 220 F 1. VL, 1.0 V/div 2. IL, 500 mA/div 3. VOUT, 50 mV/div, AC coupled 2 s/div VOUT = 1.9 V, VIN = 1.2 V, IO = 500 mA, L = 10 H, COUT = 220 F 1. VL, 1.0 V/div 2. IL, 500 mA/div 3. VOUT, 50 mV/div, AC coupled Figure 51. NCP1450ASN19T1 Operating Waveforms (Medium Load) Figure 52. NCP1450ASN19T1 Operating Waveforms (Heavy Load) 2 s/div VOUT = 3.0 V, VIN = 1.8 V, IO = 20 mA, L = 10 H, COUT = 220 F 1. VL, 2.0 V/div 2. IL, 500 mA/div 3. VOUT, 50 mV/div, AC coupled 2 s/div VOUT = 3.0 V, VIN = 1.8 V, IO = 500 mA, L = 10 H, COUT = 220 F 1. VL, 2.0 V/div 2. IL, 500 mA/div 3. VOUT, 50 mV/div, AC coupled Figure 53. NCP1450ASN30T1 Operating Waveforms (Medium Load) Figure 54. NCP1450ASN30T1 Operating Waveforms (Heavy Load) 2 s/div VOUT = 5.0 V, VIN = 3.0 V, IO = 20 mA, L = 10 H, COUT = 220 F 1. VL, 2.0 V/div 2. IL, 500 mA/div 3. VOUT, 50 mV/div, AC coupled 2 s/div VOUT = 5.0 V, VIN = 3.0 V, IO = 500 mA, L = 10 H, COUT = 220 F 1. VL, 2.0 V/div 2. IL, 500 mA/div 3. VOUT, 50 mV/div, AC coupled Figure 55. NCP1450ASN50T1 Operating Waveforms (Medium Load) Figure 56. NCP1450ASN50T1 Operating Waveforms (Heavy Load) http://onsemi.com 13 NCP1450A VIN = 1.5 V, L = 4.7 H, COUT = 220 F 1. VOUT, 1.9 V (AC coupled), 200 mV/div 2. IO, 1.0 mA to 100 mA VIN = 1.5 V, L = 4.7 H, COUT = 220 F 1. VOUT, 1.9 V (AC coupled), 200 mV/div 2. IO, 100 mA to 1.0 mA Figure 57. NCP1450ASN19T1 Load Transient Response Figure 58. NCP1450ASN19T1 Load Transient Response VIN = 2.0 V, L = 4.7 H, COUT = 220 F 1. VOUT, 3.0 V (AC coupled), 200 mV/div 2. IO, 1.0 mA to 100 mA VIN = 2.0 V, L = 4.7 H, COUT = 220 F 1. VOUT, 3.0 V (AC coupled), 200 mV/div 2. IO, 100 mA to 1.0 mA Figure 59. NCP1450ASN30T1 Load Transient Response Figure 60. NCP1450ASN30T1 Load Transient Response VIN = 3.0 V, L = 4.7 H, COUT = 220 F 1. VOUT, 5.0 V (AC coupled), 200 mV/div 2. IO, 1.0 mA to 100 mA VIN = 3.0 V, L = 4.7 H, COUT = 220 F 1. VOUT, 5.0 V (AC coupled), 200 mV/div 2. IO, 100 mA to 1.0 mA Figure 61. NCP1450ASN50T1 Load Transient Response Figure 62. NCP1450ASN50T1 Load Transient Response http://onsemi.com 14 NCP1450A 3.2 VOUT, OUTPUT VOLTAGE (V) VOUT, OUTPUT VOLTAGE (V) 2.1 VIN = 1.5 V 2.0 1.9 1.8 VIN = 0.9 V NCP1450ASN19T1 L = 10 H Q = MMJT9410 Rb = 560 Cb = 0.003 F COUT = 220 F TA = 25°C VIN = 1.2 V 1.7 1.6 0 200 400 600 800 VIN = 2.5 V NCP1450ASN30T1 L = 10 H Q = MMJT9410 Rb = 560 Cb = 0.003 F COUT = 220 F TA = 25°C VIN = 1.5 V 2.9 VIN = 1.2 V VIN = 0.9 V 2.8 0 200 400 600 800 1000 IO, OUTPUT CURRENT (mA) IO, OUTPUT CURRENT (mA) Figure 63. NCP1450ASN19T1 Output Voltage vs. Output Current (Ext. BJT) Figure 64. NCP1450ASN30T1 Output Voltage vs. Output Current (Ext. BJT) 100 VIN = 4.5 V VIN = 4.0 V 5.1 VIN = 1.5 V VIN = 2.5 V VIN = 3.0 V 5.0 4.9 NCP1450ASN50T1 L = 10 H Q = MMJT9410 Rb = 560 Cb = 0.003 F COUT = 220 F TA = 25°C VIN = 2.0 V VIN = 1.2 V 4.8 VIN = 0.9 V 4.7 0 200 400 600 800 60 NCP1450ASN19T1 L = 10 H Q = MMJT9410 Rb = 560 Cb = 0.003 F COUT = 220 F TA = 25°C 40 VIN = 0.9 V 0 0.01 1000 0.1 1 10 100 IO, OUTPUT CURRENT (mA) IO, OUTPUT CURRENT (mA) Figure 65. NCP1450ASN50T1 Output Voltage vs. Output Current (Ext. BJT) Figure 66. NCP1450ASN19T1 Efficiency vs. Output Current (Ext. BJT) 1000 100 VIN = 2.5 V VIN = 2.0 V VIN = 1.5 V VIN = 1.2 V VIN = 0.9 V NCP1450ASN30T1 L = 10 H Q = MMJT9410 Rb = 560 Cb = 0.003 F COUT = 220 F TA = 25°C 40 20 0 0.01 EFFICIENCY (%) 60 VIN = 1.2 V 20 100 80 VIN = 1.5 V 80 EFFICIENCY (%) VOUT, OUTPUT VOLTAGE (V) VIN = 2.0 V 3.0 2.7 1000 5.2 EFFICIENCY (%) 3.1 0.1 1 10 100 VIN = 4.0 V VIN = 3.0 V 80 VIN = 2.5 V VIN = 2.0 V VIN = 0.9 V 60 VIN = 4.5 V 40 NCP1450ASN50T1 L = 10 H Q = MMJT9410 Rb = 560 Cb = 0.003 F COUT = 220 F TA = 25°C VIN = 1.5 V VIN = 1.2 V 20 1000 0 0.01 0.1 1 10 100 IO, OUTPUT CURRENT (mA) IO, OUTPUT CURRENT (mA) Figure 67. NCP1450ASN30T1 Efficiency vs. Output Current (Ext. BJT) Figure 68. NCP1450ASN50T1 Efficiency vs. Output Current (Ext. BJT) http://onsemi.com 15 1000 10 100 IIN, NO LOAD INPUT CURRENT (mA) IIN, NO LOAD INPUT CURRENT (mA) NCP1450A NCP1450ASNXXT1 L = 10 H Q = NTGS3446T1 COUT = 220 F TA = 25°C 1 VOUT = 5.0 V 0.1 VOUT = 3.0 V VOUT = 1.9 V 0.01 1 2 3 4 A. VOUT = 1.9 V, Rb = 1 k B. VOUT = 3.0 V, Rb = 1 k C. VOUT = 5.0 V, Rb = 1 k D. VOUT = 1.9 V, Rb = 560 E. VOUT = 3.0 V, Rb = 560 F. VOUT = 5.0 V, Rb = 560 F C 10 E B NCP1450ASNXXT1 L = 10 H Q = MMJT9410 COUT = 220 F TA = 25°C 1 D 0.1 A 0.01 5 0 1 2 3 4 VIN, INPUT VOLTAGE (V) VIN, INPUT VOLTAGE (V) Figure 69. NCP1450ASNXXT1 No Load Input Current vs. Input Voltage (Using MOSFET) Figure 70. NCP1450ASNXXT1 No Load Input Current vs. Input Voltage (Using BJT) 5 Components Supplier ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ Parts Supplier Part Number Description Phone Inductor: L1, L2 Sumida Electric Co. Ltd. CD54−100MC Inductor 10 H/1.44 A (852) 2880−6688 Schottky Diode: D1, D2 ON Semiconductor MBRM110L Schottky Power Rectifier (852) 2689−0088 MOSFET: Q1 ON Semiconductor NTGS3446T1 Power MOSFET N−Channel (852) 2689−0088 BJT: Q2 ON Semiconductor MMJT9410 Bipolar Power Transistor (852) 2689−0088 Output Capacitor: C1, C3 KEMET Electronics Corp. T494D227K006AS Low ESR Tantalum Capacitor 220 F/6.0 V (852) 2305−1168 Input Capacitor: C2, C4 KEMET Electronics Corp. T491C106K016AS Low Profile Tantalum Capacitor 10 F/16 V (852) 2305−1168 http://onsemi.com 16 NCP1450A DETAILED OPERATING DESCRIPTION Operation Soft Start The NCP1450A series are monolithic power switching controllers optimized for battery powered portable products where large output current is required. The NCP1450A series are low noise fixed frequency voltage−mode PWM DC−DC controllers, and consist of startup circuit, feedback resistor divider, reference voltage, oscillator, loop compensation network, PWM control circuit, and low ON resistance driver. Due to the on−chip feedback resistor and loop compensation network, the system designer can get the regulated output voltage from 1.8 V to 5.0 V with 0.1 V stepwise with a small number of external components. The quiescent current is typically 93 A (VOUT = 2.7 V, fOSC = 180 kHz), and can be further reduced to about 1.5 A when the chip is disabled (VCE t 0.3 V). The NCP1450A operation can be best understood by referring to the block diagram in Figure 2. The error amplifier monitors the output voltage via the feedback resistor divider by comparing the feedback voltage with the reference voltage. When the feedback voltage is lower than the reference voltage, the error amplifier output will decrease. The error amplifier output is then compared with the oscillator ramp voltage at the PWM controller. When the ramp voltage is higher than the error amplifier output, the high−side driver is turned on and the low−side driver is turned off which will then switch on the external transistor; and vice versa. As the error amplifier output decreases, the high−side driver turn−on time increases and duty cycle increases. When the feedback voltage is higher than the reference voltage, the error amplifier output increases and the duty cycle decreases. When the external power switch is on, the current ramps up in the inductor, storing energy in the magnetic field. When the external power switch is off, the energy stored in the magnetic field is transferred to the output filter capacitor and the load. The output filter capacitor stores the charge while the inductor current is higher than the output current, then sustains the output voltage until the next switching cycle. As the load current is decreased, the switch transistor turns on for a shorter duty cycle. Under the light load condition, the controller will skip switching cycles to reduce power consumption, so that high efficiency is maintained at light loads. There is a soft start circuit in NCP1450A. When power is applied to the device, the soft start circuit first pumps up the output voltage to approximately 1.5 V at a fixed duty cycle. This is the voltage level at which the controller can operate normally. In addition to that, the startup capability with heavy loads is also improved. Oscillator The oscillator frequency is internally set to 180 kHz at an accuracy of "20% and with low temperature coefficient of 0.11%/°C. Regulated Converter Voltage (VOUT) The VOUT is set by an integrated feedback resistor network. This is trimmed to a selected voltage from 1.8 V to 5.0 V range in 100 mV steps with an accuracy of "2.5%. Compensation The device is designed to operate in continuous conduction mode. An internal compensation circuit was designed to guarantee stability over the full input/output voltage and full output load range. Enable/Disable Operation The NCP1450A series offer IC shutdown mode by chip enable pin (CE pin) to reduce current consumption. When voltage at pin CE is equal or greater than 0.9 V, the chip will be enabled, which means the controller is in normal operation. When voltage at pin CE is less than 0.3 V, the chip is disabled, which means IC is shutdown. Important: DO NOT apply a voltage between 0.3 V to 0.9 V to pin CE as this is the CE pin’s hysteresis voltage range. Clearly defined output states can only be obtained by applying voltage out of this range. http://onsemi.com 17 NCP1450A APPLICATION CIRCUIT INFORMATION Step−up Converter Design Equations Calculate the maximum inductance value which can generate the desired current output and the preferred delta inductor current to average inductor current ratio: The NCP1450A PWM step−up DC−DC controller is designed to operate in continuous conduction mode and can be defined by the following equations. External components values can be calculated from these equations, however, the optimized value should obtained through experimental results. Lv Determine the average inductor current and peak inductor current: ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ Calculation Equation D V ) VD * VIN v OUT VOUT ) VD * VS IL IO (1 * D) L (VOUT ) VD * VIN)(1 * D)2 f IO DIR IPK IL (1 ) DIR) 2 Q ( IL * IO)(1 * D) f Q [ ) ( IL * IO) ESR COUT VPP NOTES: D − On−time duty cycle IL − Average inductor current IPK − Peak inductor current DIR − Delta inductor current to average inductor current ratio IO − Desired dc output current VIN − Nominal operating dc input voltage VOUT − Desired dc output voltage VD − Diode forward voltage VS − Saturation voltage of the external transistor switch − Charge stores in the COUT during charging up Q ESR − Equivalent series resistance of the output capacitor 1 IL + + 1.57 A 1 * 0.364 IPK + 1.57A (1 ) 0.2) + 1.73A 2 Therefore, a 12 H inductor with saturation current larger than 1.73 A can be selected as the initial trial. Calculate the delta charge stored in the output capacitor during the charging up period in each switching cycle: Q + (1.57A * 1A)(1 * 0.364) + 2.01 C 18000Hz Determine the output capacitance value for the desired output ripple voltage: Assume the ESR of the output capacitor is 0.15 , COUT u 2.01C 100mV * (1.57A * 1A) 0.15 + 138.6 F Therefore, a Tantalum capacitor with value of 150 F to 220 F and ESR of 0.15 can be used as the output capacitor. However, according to experimental result, 220F output capacitor gives better overall operational stability and smaller ripple voltage. External Component Selection Inductor Selection Design Example The NCP1450A is designed to work well with a 6.8 to 12 H inductors in most applications 10 H is a sufficiently low value to allow the use of a small surface mount coil, but large enough to maintain low ripple. Lower inductance values supply higher output current, but also increase the ripple and reduce efficiency. Higher inductor values reduce ripple and improve efficiency, but also limit output current. The inductor should have small DCR, usually less than 1, to minimize loss. It is necessary to choose an inductor with a saturation current greater than the peak current which the inductor will encounter in the application. It is supposed that a step−up DC−DC controller with 3.3 V output delivering a maximum 1000 mA output current with 100 mV output ripple voltage powering from a 2.4 V input is to be designed. Design parameters: VIN = 2.4 V VOUT = 3.3 V IO = 1.0 A Vpp = 100 mV f = 180 kHZ DIR = 0.2 (typical for small output ripple voltage) Assume the diode forward voltage and the transistor saturation voltage are both 0.3 V. Determine the maximum steady state duty cycle at VIN = 2.4 V: D+ (3.3 V ) 0.3 V * 2.4 V)(1 * 0.364)2 + 13.5 H 180000 Hz 1 A 0.2 3.3 V ) 0.3 V * 2.4 V + 0.364 3.3 V ) 0.3 V * 0.3 V http://onsemi.com 18 NCP1450A Diode more efficient switch than a BJT transistor. However, the MOSFET requires a higher voltage to turn on as compared with BJT transistors. An enhancement N−channel MOSFET can be selected by the following guidelines: 1. Low ON−resistance, RDS(on), typically < 0.1 . 2. Low gate threshold voltage, VGS(th), must be < VOUT, typically < 1.5 V, it is especially important for the low VOUT device, like VOUT = 1.9 V. 3. Rated continuous drain current, ID, should be larger than the peak inductor current, i.e. ID > IPK. 4. Gate capacitance should be 1200 pF or less. For bipolar NPN transistor, medium power transistor with continuous collector current typically 1 A to 5 A and VCE(sat) < 0.2 V should be employed. The driving capability is determined by the DC current gain, HFE, of the transistor and the base resistor, Rb; and the controller’s EXT pin must be able to supply the necessary driving current. The diode is the largest source of loss in DC−DC converters. The most importance parameters which affect their efficiency are the forward voltage drop, VD , and the reverse recovery time, trr. The forward voltage drop creates a loss just by having a voltage across the device while a current flowing through it. The reverse recovery time generates a loss when the diode is reverse biased, and the current appears to actually flow backwards through the diode due to the minority carriers being swept from the P−N junction. A Schottky diode with the following characteristics is recommended: Small forward voltage, VF t 0.3 V Small reverse leakage current Fast reverse recovery time/switching speed Rated current larger than peak inductor current, Irated u IPK Reverse voltage larger than output voltage, Vreverse u VOUT Rb can be calculated by the following equation: V 0.7 0.4 Rb + OUT * * | IEXTH| Ib Input Capacitor The input capacitor can stabilize the input voltage and minimize peak current ripple from the source. The value of the capacitor depends on the impedance of the input source used. Small Equivalent Series Resistance (ESR) Tantalum or ceramic capacitor with a value of 10 F should be suitable. I Ib + PK HFE Since the pulse current flows through the transistor, the exact Rb value should be finely tuned by the experiment. Generally, a small Rb value can increase the output current capability, but the efficiency will decrease due to more energy is used to drive the transistor. Moreover, a speed−up capacitor, Cb, should be connected in parallel with Rb to reduce switching loss and improve efficiency. Cb can be calculated by the equation below: Output Capacitor The output capacitor is used for sustaining the output voltage when the external MOSFET or bipolar transistor is switched on and smoothing the ripple voltage. Low ESR capacitor should be used to reduce output ripple voltage. In general, a 100 F to 220 F low ESR (0.10 to 0.30 ) Tantalum capacitor should be appropriate. Cb v 2 Rb 1 fOSC 0.7 It is due to the variation in the characteristics of the transistor used. The calculated value should be used as the initial test value and the optimized value should be obtained by the experiment. External Switch Transistor An enhancement N−channel MOSFET or a bipolar NPN transistor can be used as the external switch transistor. For enhancement N−channel MOSFET, since enhancement MOSFET is a voltage driven device, it is a External Component Reference Data VOUT Inductor Model Inductor Value External Transistor Diode Output Capacitor NCP1450ASN19T1 1.9 V CD54 12 H NTGS3446T1 MBRM110L 220 F NCP1450ASN30T1 3.0 V CD54 10 H NTGS3446T1 MBRM110L 220 F NCP1450ASN50T1 5.0 V CD54 10 H NTGS3446T1 MBRM110L 220 F NCP1450ASN19T1 1.9 V CD54 12 H MMJT9410 MBRM110L 220 F NCP1450ASN30T1 3.0 V CD54 10 H MMJT9410 MBRM110L 220 F NCP1450ASN50T1 5.0 V CD54 10 H MMJT9410 MBRM110L 220 F Device http://onsemi.com 19 NCP1450A ON Semiconductor representative for availability. The evaluation board schematic diagrams are shown in Figures 73 and 74. An evaluation board of NCP1450A has been made in the small size of 89 mm x 51 mm. The artwork and the silk screen of the surface−mount evaluation board PCB are shown in Figures 71 and 72. Please contact your 51 mm 89 mm Figure 71. NCP1450A PWM Step−up DC−DC Controller Evaluation Board Silkscreen 51 mm 89 mm Figure 72. NCP1450A PWM Step−up DC−DC Controller Evaluation Board Artwork (Component Side) http://onsemi.com 20 NCP1450A L1 10 H D1 MBRM110L JP1 TP1 VIN TP3 VOUT NTGS3446T1 ON CE OFF NCP1450A C2 10 F CE 1 OUT 2 C3 NC 0.1 F 3 TP2 GND EXT 5 Q1 C1 220 F IC1 GND 4 TP4 GND Figure 73. NCP1450A Evaluation Board Schematic Diagram 1 (Step−up DC−DC Converter Using External MOSFET Switch) L2 10 H D2 MBRM110L JP2 C5 10 F TP6 GND TP7 VOUT CE 1 ON CE OFF OUT 2 C6 0.1 F NC 3 Rb 560 EXT 5 NCP1450A TP5 VIN Q2 MMJT9410 C4 220 F IC2 GND 4 Cb 3000 pF TP8 GND Figure 74. NCP1450A Evaluation Board Schematic Diagram 2 (Step−up DC−DC Converter Using External Bipolar Transistor Switch) PCB Layout Hints Grounding Output Capacitor One point grounding should be used for the output power return ground, the input power return ground, and the device switch ground to reduce noise. In Figure 73, e.g.: C2 GND, C1 GND, and IC1 GND are connected at one point in the evaluation board. The input ground and output ground traces must be thick enough for current to flow through and for reducing ground bounce. The output capacitor should be placed close to the output terminals to obtain better smoothing effect on the output ripple. Switching Noise Decoupling Capacitor A 0.1 F ceramic capacitor should be placed close to the OUT pin and GND pin of the NCP1450A to filter the switching spikes in the output voltage monitored by the OUT pin. Power Signal Traces Low resistance conducting paths should be used for the power carrying traces to reduce power loss so as to improve efficiency (short and thick traces for connecting the inductor L can also reduce stray inductance), e.g.: short and thick traces listed below are used in the evaluation board: 1. Trace from TP1 to L1 2. Trace from L1 to anode pin of D1 3. Trace from cathode pin of D1 to TP3 http://onsemi.com 21 NCP1450A PACKAGE DIMENSIONS TSOP−5 SN SUFFIX CASE 483−02 ISSUE E NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: MILLIMETER. 3. MAXIMUM LEAD THICKNESS INCLUDES LEAD FINISH THICKNESS. MINIMUM LEAD THICKNESS IS THE MINIMUM THICKNESS OF BASE MATERIAL. 4. A AND B DIMENSIONS DO NOT INCLUDE MOLD FLASH, PROTRUSIONS, OR GATE BURRS. D S 5 4 1 2 3 B L G DIM A B C D G H J K L M S A J C 0.05 (0.002) H M K MILLIMETERS MIN MAX 2.90 3.10 1.30 1.70 0.90 1.10 0.25 0.50 0.85 1.05 0.013 0.100 0.10 0.26 0.20 0.60 1.25 1.55 0_ 10 _ 2.50 3.00 INCHES MIN MAX 0.1142 0.1220 0.0512 0.0669 0.0354 0.0433 0.0098 0.0197 0.0335 0.0413 0.0005 0.0040 0.0040 0.0102 0.0079 0.0236 0.0493 0.0610 0_ 10 _ 0.0985 0.1181 SOLDERING FOOTPRINT* 0.95 0.037 1.9 0.074 2.4 0.094 1.0 0.039 0.7 0.028 SCALE 10:1 mm Ǔ ǒinches *For additional information on our Pb−Free strategy and soldering details, please download the ON Semiconductor Soldering and Mounting Techniques Reference Manual, SOLDERRM/D. ON Semiconductor and are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice to any products herein. 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